Hi all, I think it's about time for me to replace my clutch and I was reading up a lot about people running into disengagement issues with the Fidanza SMF and Spec Stage 2 Clutch Kit. The best solution I found for a SMF & sprung clutch was from @Jeff Lange where he recommends:
Flywheel: PGEAR FW1224005 or Exedy Australia LEK-8766SMF (Exedy only comes as a kit - flywheel not sold separately, old part number ZAP-211775)
Pressure Plate: Lexus 31210-53032, SPEC SLC251, SPEC SLC252, or Lexus F-Sport PTR15-53080 (F-Sport only sold as a kit - pressure plate not sold separately, discontinued)
Clutch Disc: Toyota 31250-60500
Release Bearing: Toyota/Lexus 90903-63001 and 96152-00500
Release Fork E-Clip: Toyota/Lexus 96160-00900

in this thread: https://www.clublexus.com/forums/is-...nsmission.html

Currently, my car is basically stock with the exception of an Invidia Q300 and some cheapo intake (HPS I think)

I'm planning on putting on PPE headers with RR-Racing's Tune in the future and was wondering if I would need the extra clamping force I'd get off of a SMF setup or if I would be fine with just a OEM replacement (LUK Repset 16114)
If I should just stick to the DMF, what is the best replacement clutch set that would work with the OEM flywheel?

I know this is a lot of information I'm throwing out, I'm just still soaking in Jeff's clutch post lol

 

To eliminate the shake everyone gets from the SMF, lower your rearend ratio to something easier for the little 2.5L mouse motor to climb; stiffen the engine, transmission and differential mounts; and delete the delay valve so you can slip the clutch like a normal driver.

The first issue is the 3.73:1 ratio through the pegleg. When the clutch delay valve pops and clamps the disk to the flywheel, the engine and transmission buck around inside all of the rubber mounts the factory gave the grandmothers to grab their groceries with. The open differential bucks the subframe around on it's rubber as the power wheel pushes against all the rubber on the 5 links suspending the hub, and also yaws the differential snout in relation to the transmission. When you swap to a 4.10:1 ratio Y38 differential like I did--or go sportier with the Y58's 4.30:1--not only are you bringing that torque hill down to something more manageable than factory, you're also applying power through both tires, which reduces the amount of bouncing the suspension does while actually biasing torque, instead of the on/off you get from an open diff. I still maintain that the best mod I've done so far is the Y38 diff, and I just added 500cc of displacement to the thing.

Second is the mounts. If nothing else, replace your worn factory ones with newer ones. I recently learned that the Kein IS300 R154 mounts don't bolt up like you want them to, the stud pattern is like 5mm offset from the IS250's mount, and the IS250 mount wants a dropped crossmember. Bolts to the gearbox just fine. Once I get a convenient way to get the car in the air again, I'll be looking into fabricating a transmission crossmember for the Kein mount. That factory mush has got to go if I want to apply any real power through it.

Third is the clutch delay valve JL replaced with the GRMN unit in that thread. Haven't done mine yet, but my plan of attack is to take the bolts off the cover and see if I can remove it's guts. If not, I'll drill a new passage, fab a new block, or crimp my own custom adaptor hose, whichever happens first. Reason to do that is so you can feel what your clutch is doing again. I ain't seen inside it yet, but my assumption is that there's a diaphragm and a spring in there that don't allow fluid to the slave cylinder until a certain pressure is reached and then it's all "OK, NOW!!!". When you go back to an uninterrupted column of fluid between the piston under your foot and the piston holding the disk back, it should feel more controlled, which'll let you know when you're giving the gearbox the delirium tremens.

Hope that helps.